The geomagnetic field was quiet to unsettled on August 17. Solar wind speed at SOHO ranged between 297 and 393 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. A disturbance began early on August 18, the source is uncertain but may be due to effects from CH1165.
Solar flux density measured at 20h UT on 2.8 GHz was 151.9 - decreasing 20.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 152.24. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 32202211 (planetary), 32311422 (Boulder), 52213231 (Andenes).
The background x-ray flux is at the class B8 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 269) and in 12 active regions using 1K resolution (SN: 170) SDO/HMI images.
Region 13397 [N20W84] decayed slowly and was
mostly quiet.
Region 13403 [N26W21] was mostly quiet and stable. C1 flares: C1.2 @
06:13, C1.7 @ 07:36, C1.3 @ 23:40 UT
Region 13404 [S09E21] was mostly quiet and stable.
Region 13405 [N10E35] displayed no significant changes and was mostly
quiet.
Region 13406 [S17W47] decayed slowly and quietly.
Region 13407 [S18W03] developed slowly and quietly.
Region 13408 [S19W18] decayed slowly and quietly.
Region 13409 [N21W28] decayed slowly and was mostly quiet. C1 flares:
C1.2 @ 05:43 UT
New region 13411 [N13E49] rotated into view on August 15 and was
numbered 2 days later by SWPC. C1 flares: C1.2 @ 15:25 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8848 [N22W37] decayed slowly and quietly.
S8850 [N24W05] was quiet and stable.
S8869 [N12E11] decayed slowly and quietly.
S8872 [S25W02] was quiet and stable.
New region S8874 [N31E84] rotated into view with a mature spot.
New region S8875 [S15E17] was observed with tiny spots in an old
plage area.
An active region behind the
southeast limb produced a few flares including a C1.3 flare at 14:00, a C1.2
flare at 15:46, C1.0 flare at 16:11and a C1.2 flare at 16:34 UT
An active region behind the northwest limb produced a C1.1 flare at 06:45 UT
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.6 | 02:45 | behind SW limb | 13394 | GOES18 | LDE, moderate type II radio sweep, backsided partial halo CME |
| C2.3 | 08:32 | behind NW limb | 13395 | GOES16 | |
| C5.2 | 12:40 | N19W80 | 13397 | GOES16 | weak type II radio sweep |
| C2.7 | 13:30 | behind SE limb | GOES16 | ||
| C3.5 | 14:20 | behind SE limb | GOES16 | ||
| C2.2 | 17:29 | behind SE limb | GOES16 | attributed to AR 13397 by SWPC |
August 15-17: No obviously Earth directed CMEs were observed.
[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A southern hemisphere coronal hole (CH1165) rotated across the central meridian on August 13-14.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on August 17 due to effects from CH1165. Quiet conditions are likely on August 18-19.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole
could reach Earth within the next 5 days. When the high speed
stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 13397 | 2023.08.06 2023.08.07 |
2 | 2 | 1 | N17W83 | 0020 | CAO | CRO |
 |
 |
location: N20W84 |
| 13399 | 2023.08.06 2023.08.09 |
S15W76 | location: S16W47 | ||||||||
| S8839 | 2023.08.08 | S28W37 | |||||||||
| S8845 | 2023.08.10 | S19W58 | |||||||||
| S8848 | 2023.08.10 | 1 | N22W37 | 0001 | AXX |
 |
 |
||||
| S8850 | 2023.08.11 | 8 | N24W05 | 0020 | BXO |
 |
 |
||||
| S8851 | 2023.08.11 | N10W34 |
 |
||||||||
| 13403 | 2023.08.13 2023.08.13 |
16 | 34 | 16 | N25W22 | 0180 | DAI | DAI |
 |
 |
area: 0310 location: N26W21 |
| 13406 | 2023.08.13 2023.08.15 |
6 | 2 | S18W46 | 0010 | CRO |
 |
 |
|||
| 13404 | 2023.08.13 2023.08.14 |
3 | 6 | 3 | S09E20 | 0030 | CAO | CAO |
 |
 |
area: 0050 location: S09E21 |
| 13409 | 2023.08.13 2023.08.16 |
7 | 12 | 7 | N21W30 | 0020 | CRO | CRO |
 |
 |
area: 0030 location: N21W28 |
| 13405 | 2023.08.13 2023.08.14 |
4 | 13 | 7 | N11E38 | 0160 | ESO | ESO |
 |
 |
area: 0240 location: N10E35 |
| 13407 | 2023.08.14 2023.08.15 |
8 | 17 | 7 | S18W04 | 0200 | DSI | DAO |
 |
 |
area: 0360 location: S18W03 |
| S8861 | 2023.08.14 | S06E15 | |||||||||
| S8863 | 2023.08.14 | N27E40 | |||||||||
| S8864 | 2023.08.14 | N19W04 | |||||||||
| S8865 | 2023.08.14 | S09W21 | |||||||||
| S8866 | 2023.08.14 | S33W03 | |||||||||
| 13411 | 2023.08.15 2023.08.17 |
1 | 2 | 2 | N14E54 | 0070 | HSX | CSO |
 |
 |
location: N13E49 area: 0120 |
| 13408 | 2023.08.15 2023.08.16 |
3 | 3 | 1 | S18W18 | 0010 | BXO | BXO |
 |
 |
area: 0030 location: S19W18 |
| 13410 | 2023.08.16 | 1 | S30W48 | 0010 | AXX | for the second consecutive day SWPC reports a spot at a location where there are no spots | |||||
| S8869 | 2023.08.16 | 5 | N12E11 | 0010 | BXO |
 |
 |
||||
| S8870 | 2023.08.16 | N14E04 |
 |
||||||||
| S8871 | 2023.08.16 | S13W47 |
 |
||||||||
| S8872 | 2023.08.16 | 4 | 1 | S25W02 | 0009 | CRO |
 |
 |
|||
| S8873 | 2023.08.16 | N15E19 |
 |
||||||||
| S8874 | 2023.08.17 | 1 | 1 | N31E84 | 0090 | HSX |
 |
||||
| S8875 | 2023.08.17 | 5 | 2 | S15E17 | 0010 | BXO |
 |
||||
| Total spot count: | 45 | 119 | 50 | ||||||||
| Sunspot number: | 135 | 269 | 170 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 78 | 161 | 92 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 149 | 148 | 136 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.0 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.6 (+5.6) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | 113.3 (+6.7) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (119.1 projected, +5.8) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (124.4 projected, +5.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (130.5 projected, +6.1) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.9 | (136.1 projected, +5.6) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 163.4 | (139.3 projected, +3.2) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 159.1 | (139.7 projected, +0.4) | 8.15 |
| 2023.08 | 161.4 (1) | 59.7(2A) / 108.8 (2B) / 140.4 (2C) | (141.5 projected, +1.8) | (8.1) | |
| 2023.09 | (145.0 projected, +3.5) | ||||
| 2023.10 | (146.8 projected, +1.8) | ||||
| 2023.11 | (149.4 projected max SC25, +2.6) | ||||
| 2023.12 | (148.6 projected, -0.8) | ||||
| 2024.01 | (145.7 projected, -2.9) | ||||
| 2024.02 | (144.3 projected, -1.4) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap indices.
4) Source: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
